Toy Sensitive to Human Touch

ABSTRACT

A toy including at least one capacitive sensor comprising a metal plate constituting one of the two plates of a capacitor, the second plate being constituted by a portion of a living being in the proximity of the toy, at least one effects generator; and a control circuit including means for causing effects to take place in response to stimulation of said capacitive sensor; the toy being characterized in that said metal plate of said at least one capacitive sensor is used as an antenna for picking tip radio frequency transmission from said portion of a living being in the proximity of the toy.

The present invention relates to a toy including means for detecting the approach of a portion of a living being, in particular for the purpose of triggering an effect, e.g. a sound effect, a light effect, or even a movement performed by said toy. More particularly, the invention relates to a doll including means for detection by the capacitive effect, combined with other detection systems. The field concerned is that of toys and the electronics in such toys.

It is known to use capacitive effect detectors for actuating effects in a toy such as a doll. The US patent application published under the No. US 2004/0043696 discloses a toy including a capacitive effect contactless detection system having a conductive receiver plate, an effect activation circuit, and means for interconnecting those two elements. The receiver plates can be hidden inside the toy so as to avoid any detection system being visible or apparent on the outside of the toy. When an object comes close to one of the receiver plates, the capacitance measured at that plate is modified. Consequently, by measuring the time constant of an RC circuit, equal to the product R×C where C is the capacitance of the plate and R is a resistance in the circuit, it is possible to detect variations in said time constant while discharging the RC circuit. The RC circuit discharge time is thus measured and then compared with a reference value in order to determine whether the capacitance has changed. Such a variation in the discharge time means that an object is in the proximity of the doll or the toy.

However, if a metal plate is brought up to the toy, the toy detects the presence of the plate and therefore triggers its effects. The toy thus appears to respond even though no portion of a living being is in the proximity of the sensor. Such interference can be caused in this way by any nearby metal object of large weight or area.

An objective of the present invention is to remedy the above-mentioned drawbacks. The invention thus proposes a detection system avoiding that kind of interference. It is based on the fact that the body of a living being transmits radio waves. More precisely, the electrical power distribution network emits radio waves having the same waveform as the electricity it distributes. These waves are picked up by nearby living beings and re-emitted.

The present invention thus provides a toy including at least one capacitive sensor comprising a metal plate constituting one of the two plates of a capacitor, the second plate being constituted by a portion of a living being in the proximity of the toy,

at least one effects generator; and

a control circuit including means for causing effects to take place in response to stimulation of said capacitive sensor;

the toy being characterized in that said metal plate of said at least one capacitive sensor is used as an antenna for picking up radio frequency transmission from said portion of a living being in the proximity of the toy.

Advantageously, the radio frequency transmission is at the frequency of an electrical power distribution network.

In the preferred embodiment, the toy of the invention advantageously comprises:

-   -   means for charging and discharging the capacitor of said at         least one capacitive sensor;     -   a counter for measuring the discharge time of said at least one         capacitive sensor;     -   means for starting the counter when the capacitor is charged,         and means for stopping the counter when the capacitor is         discharged;     -   a control circuit connected to the counter and having means for         storing a plurality of discharge times issued by the counter,         said plurality of discharge times constituting a collection, the         control circuit comprising means for analyzing the collection of         a plurality of discharge times, and means for detecting         variation in the mean value of the collection relative to the         mean value of the preceding collection, the control circuit also         comprising means for comparing variation in the values of the         discharge times within a single collection with a sinusoidal         signal of frequency substantially equal to the frequency of an         electrical power distribution network;     -   a resistor which is located between ground and the base of the         first plate of the capacitor of said at least one capacitive         sensor, the resistor and the capacitor thus constituting an RC         circuit; and     -   a variable frequency radio frequency generator generating an         electromagnetic field, at least one accessory including a         passive resonant circuit constituted by an inductor connected in         series with a capacitor and responsive to an electromagnetic         field at a determined frequency; and means for determining the         presence of at least one accessory and for stimulating the         effects generator in such a manner as to cause it to produce an         effect.

In the preferred embodiment, the invention provides a doll having a plurality of capacitive sensors situated at various locations on the doll.

In another aspect, the invention provides a method of detecting human presence for a toy including a capacitive sensor having a metal plate constituting one of the two plates of a capacitor, the second plate of the capacitor being constituted by a portion of a living being in the proximity of the toy, said method comprising at least the steps consisting in:

-   -   making a collection comprising a plurality of values for the         discharge time of the capacitor;     -   comparing the mean value of the collection with a reference         discharge time value;     -   comparing the mean value of the collection with the mean value         of the preceding collection; and     -   comparing any variations between the discharge time values of         the capacitor within the collection with a sinusoidal signal of         frequency substantially equal to the frequency of the electrical         power distribution network.

Advantageously, this second aspect of the invention comprises the following characteristics:

-   -   it is concluded that a portion of a living being is present when         the variations in the discharge time values present         substantially the form of said sinusoidal signal;     -   it is concluded that a portion of a living being is present if         the mean value of the current collection is substantially equal         to the mean value of the preceding collection, and if it was         previously concluded that a portion of a living being was         present;     -   it is concluded that no portion of a living: being is present         when the mean value of the current collection is substantially         equal to a reference value;     -   the reference value is a function of external conditions; and     -   the collection comprises ten discharge time values.

Other features and advantages of the present invention appear from the following description of non-limiting embodiments, given with reference to the accompanying drawings, in which:

FIG. 1 is a diagram showing a doll in accordance with the invention;

FIG. 2 is a schematic of an electronic circuit associated with a capacitive sensor plate in the FIG. 1 doll;

FIG. 3 is a flow chart of the detection method of the invention implemented by the FIG. 2 circuit; and

FIG. 4 is a graph plotting variations in discharge time within a collection during a contact.

FIG. 1 shows the preferred embodiment of the invention. It shows a doll 1 having a plurality of sensors at various locations of its body. These sensors may be of several kinds. Thus, capacitive sensors 2 in accordance with the present invention are situated on the feet, one of the wrists, and one of the cheeks of the doll 1, while inductive sensors 3 are situated on the lips, the chest, and the other wrist of the doll 1. Whereas the inductive sensors 3 are used for detecting accessories that are not shown, the capacitive sensors 2 are used for detecting the presence of a portion of a living being in the proximity of the sensor. Other sensors such as gravimetric or radio sensors (not shown) could also be installed on the doll 1.

Each capacitive sensor 2 can lead to a different action depending on its location in the body of the doll 1. By means of this system, malfunction due to the presence of metal objects are avoided.

The operation of the capacitive sensors 2 is shown in FIG. 2. A capacitive sensor 2 is constituted by a detection plate 5 and a resistor 6 connected between the detection plate 5 and ground. On the approach of a portion of a human being 4, the capacitor 50 formed by the detection plate 5 and the portion of the human being 4 changes so that the discharge time of the RC circuit formed by the resistor 6 and the capacitor 50 is changed. An amplifier 7 serves to recharge the capacitor 50 so that a counter 8 measures the discharge time of the RC circuit. The counter 8 co-operates with the amplifier 7 by means of a start-count signal 81. Thus, when the capacitor 50 has been charged by the amplifier 7, the start-count signal 81 informs the counter 8 that it should start counting. Similarly, a stop-count signal 82 serves to stop the counter 8 and to inform a central processor unit (CPU) 9 that it can read the data delivered by the counter 8 on a data bus 84. The counter 8 and the CPU 9 are synchronized by means of a common clock signal 83.

Consequently, in order to start charging the capacitor 50 constituted by the detection plate 5 and the portion of the living being 4, the CPU 9 instructs the amplifier 7 to start charging by putting the signal 81 in the one state. The amplifier 7 then delivers electrical power to the detection plate 5 until it is charged. When the capacitor 50 constituted by the detection plate 5 and the portion of the living being 4 has finished being charged, the signal 81 changes to zero, thus stopping the amplifier 7 and starting the counter 8. Once the capacitor 50 constituted by the detection plate 5 and the portion of the living being 4 has been discharged, a Schmidt comparator 10 puts the stop-counting signal 82 to zero, thus stopping the counter 8 and informing the CPU 9 that it should store the discharge-time value present on the bus 84.

By repeating this operation a certain number of times, a collection of discharge time values stored in a memory (not shown in the figure) by the CPU 9 is built up, and on the basis of this collection analysis described below makes it possible to determine whether a living being is indeed in the proximity of the doll 1. This system presents the advantage of being simple and easy to implement. It can then co-operate with the CPU 9 in such a manner as to implement the method shown by the flow chart of FIG. 3.

In addition, the detection plate 5 acts as an antenna for receiving the radio waves transmitted by the nearby portion of a living being. This has the effect of causing the time required for the capacitor 50 to discharge to vary over time, with this variation presenting the form of a sinusoidal signal having the same frequency as the frequency of the electrical power distribution network.

In FIG. 3, a flow chart shows how the detection method in accordance with the invention runs. The method takes place in two distinct stages P1 and P2, P1 being the sampling stage during which a collection of discharge time values for the capacitor 50 is built up using the circuits shown in FIG. 2, and stage P2 being the analysis stage during which the data collected during the stage P1 is analyzed.

The stage P1 begins with initializing the system (S100). During this step (S100), the value of N is initialized to 10. This value determines the number of discharge times that go to making up a single collection.

As explained above when describing FIG. 2, the capacitor 50 is charged during the next step (S110). Once the capacitor 50 is charged, the counter 8 is started in the next step (S120). The capacitor 50 discharges at this time. The detector 10 serves to detect the end of capacitor discharging in the next step (S130).

Once the capacitor 50 is fully discharged, the stop-count signal is activated and the CPU stores the value presented by the counter 8 in the next step (S146). A test serves to determine the value of N (S150). If the value of N is not zero, then N is decremented in a step (S151) and another charge cycle is begun: the method returns to step (S110). When the value of N is zero in test step (S150), then the stage P1 has terminated and a collection of ten values has been built up in the memory of the CPU 9.

The stage P2 serves to analyze the data collected during the stage P1. Initially, the mean value of the collection is compared with a reference value. If the mean value is substantially equal to the reference value, then it can be concluded that there is no portion of a living being in the proximity of the detector 5 (S161). otherwise, if the mean value of the collection is not substantially equal to the reference value, then said current mean value of the collection is compared with the mean value of a preceding collection (S162). If these two mean values are substantially identical and if during the preceding cycle it was concluded that a portion of a living being was in the proximity of the detector of the invention, then it can again be concluded that said portion continues to be in the proximity of the detector. Otherwise, if the mean collection values are not identical, or if it was not decided previously that a portion of a living being was in the proximity of the detector, then the process continues to the next step (S163).

During step S163, variations in the values of discharge time around the mean value of the collection are compared with a sinusoidal signal of frequency substantially equal to the frequency of the electrical power distribution network. FIG. 4 is a graph showing the discharge times T1 to T10 of a single collection. These discharge times T1 to T10 vary about a collection mean value Tmean. During step S163, the CPU 9 looks for a sinusoidal waveform at a frequency substantially equal to the frequency of the electrical power distribution network in the variations in the values T1 to T10 of the discharge time. If, as is the case in FIG. 4, it is possible to superpose such a sinusoidal signal on the discharge time values T1 to T10, then it is concluded that a portion of a living being is present in the proximity of the detector. Otherwise, it is concluded that there is interference from a metal object (S166). The method then terminates with a conclusion step (S170) which causes effects to be activated if it has been concluded that a portion of a living being is present in the proximity of the detector.

In an embodiment, the reference value of step (S161) is readjusted as a function of external conditions such as the temperature, the pressure, or indeed the humidity of the surrounding air. 

1. A toy including at least one capacitive sensor comprising a metal plate constituting one of the two plates of a capacitor, the second plate being constituted by a portion of a living being in the proximity of the toy, at least one effects generator; and a control circuit including means for causing effects to take place in response to stimulation of said capacitive sensor; the toy being characterized in that said metal plate of said at least one capacitive sensor is used as an antenna for picking up radio frequency transmission from said portion of a living being in the proximity of the toy.
 2. The toy according to claim 1, in which the radio frequency transmission is at the frequency of an electrical power distribution network.
 3. The toy according to claim 1, including means for charging and discharging the capacitor of said at least one capacitive sensor.
 4. The toy according to claim 3, including a counter for measuring the discharge time of said at least one capacitive sensor.
 5. The toy according to claim 4, including means for starting the counter when the capacitor is charged, and means for stopping the counter when the capacitor is discharged.
 6. The toy according to claim 5, including a control circuit connected to the counter and having means for storing a plurality of discharge times issued by the counter, said plurality of discharge times constituting a collection.
 7. The toy according to claim 6, in which the control circuit includes means for analyzing the collection of a plurality of discharge times, and means for detecting variation in the mean value of the collection relative to the mean value of the preceding collection.
 8. The toy according to claim 6, in which the control circuit includes means for comparing variation in the values of the discharge times within a single collection with a sinusoidal signal of frequency substantially equal to the frequency of an electrical power distribution network.
 9. The toy according to any preceding claim in which a resistor is located between ground and the base of the first plate of the capacitor of said at least one capacitive sensor, the resistor and the capacitor thus constituting an RC circuit.
 10. The toy according to claim 1, including a variable frequency radio frequency generator generating an electromagnetic field, at least one accessory including a passive resonant circuit constituted by an inductor connected in series with a capacitor and responsive to an electromagnetic field at a determined frequency; and means for determining the presence of at least one accessory and for stimulating the effects generator in such a manner as to cause it to produce an effect.
 11. The toy according to claim 1, characterized in that it is a doll having a plurality of capacitive sensors situated at various locations of the doll.
 12. A method of detecting human presence for a toy according to any preceding claim, the toy including a capacitive sensor having a metal plate constituting one of the two plates of a capacitor, the second plate of the capacitor being constituted by a portion of a living being in the proximity of the toy, said method comprising at least the steps consisting in: making a collection comprising a plurality of values for the discharge time of the capacitor; comparing the mean value of the collection with a reference discharge time value; comparing the mean value of the collection with the mean value of the preceding collection; and comparing any variations between the discharge time values of the capacitor within the collection with a sinusoidal signal of frequency substantially equal to the frequency of the electrical power distribution network.
 13. The method according to claim 12, in which it is concluded that a portion of a living being is present when the variations in the discharge time values present substantially the form of said sinusoidal signal.
 14. The method according to claim 12, in which it is concluded that a portion of a living being is present if the mean value of the current collection is substantially equal to the mean value of the preceding collection, and if it was previously concluded that a portion of a living being was present.
 15. The method according to claim 12, in which it is concluded that no portion of a living being is present when the mean value of the current collection is substantially equal to a reference value.
 16. The method according to claim 15, in which the reference value is a function of external conditions.
 17. The method according to claim 12, in which the collection comprises ten discharge time values. 